Classically, a cam follower belonging to an injection pump comprises at least a tappet, a roller and a pin in bronze or steel. The roller and the pin are centered on a transverse axis, while the tappet extends along a longitudinal axis. The tappet is formed with two lateral flanges, delimiting an intermediate gap between them and each comprising a cylindrical bore, possibly beveled. The roller is positioned in the intermediate gap, between both flanges and bores. The pin is fitted in the two bores, such that the roller is movable in rotation relative to the pin around its axis. The pin might be then caulked, in other words plastically deformed, on both opposite ends to create a mechanical connection by press-fit in the tappet bores.
When the cam follower is in service, the roller collaborates with a cam synchronized with the internal combustion engine camshaft. The rotation of the camshaft leads to a periodic displacement of a piston of the pump that rests against the tappet, to allow fuel to be delivered. The tappet is movable back and forth along the longitudinal axis.
In practice, the angular orientation of the cam follower around its longitudinal axis induces the angular orientation of the transverse axis, pin and roller relative to this longitudinal axis. In case of incorrect orientation, the collaboration between roller and cam is improper and the roller rotation may be obstructed. In other words, an incorrect orientation around the longitudinal axis would cause malfunction of cam follower, injection pump and motor.
It is known to provide the cam follower with an anti-rotation function by fixing an additional part to the tappet. Documents WO-A-2010/048 968, U.S. Pat. No. 7,210,437 and US-A-2008/190 237 describe examples of such cam followers provided with an anti-rotation device. The device slides in a guide of a bore surrounding the tappet, thus ensuring correct orientation of the cam follower and preventing its accidental rotation around its longitudinal axis. However, that increases the number of subcomponents of these cam followers. Their assembly is made more complex and longer.